The present invention relates to automatically guided tractors, trolleys, and the like, for pursuing a pre-determined path through growth sources of crop items in general. Furthermore, the present invention relates to crop harvesting tools and manipulators for harvesting crop items hanging by stems from their growth sources.
The advantages of tending and in particular harvesting crop items using automatically guided tractors, trolleys and the like are well known and have encouraged the development of a number of such systems to achieve the same. Such advantages include greater equipment utilization, higher outputs for any given equipment base, less reliance on scarce and expensive manual labor, and the like.
For example, U.S. Pat. No. 4,482,960 to Pryor entitled "Robot Tractors" describes an electro-optical and microcomputer based method and apparatus for automatically guiding tractors and other farm machinery for the purpose of automatic crop planting, tending and harvesting. In particular, a farm tractor is guided by a microprocessor which receives information from a solid state TV camera mounted at the front of the tractor for viewing ahead of and to one side of the tractor. Optionally or alternatively, a second camera can be located at a high area at the edge of the field to track the tractor and provide an external reference frame for its operation.
This system suffers from a number of disadvantages. First, that the communication between the tractor and the microprocessor can be distorted by the growth sources therebetween, thereby interfering with the operation of the system. And second, that safety measures are required to ensure that the tractor does not "run away" from its pre-determined working area. These safety measures can be implemented as bumper type limit switches to physically shut off the tractor if the bumper comes in contact with an object, cables or laser beams delineating the working area of the tractor, and the like.
Turning now to the harvesting of crop items hanging by stems from growth sources, it is well known that practically every kind of tree or bush grown crop item, be it a fruit or vegetable, should be picked such that the stem remains attached to the body of the crop item. This is true when a crop item is picked in a unripe condition because proper ripening will only occur if the stem remains attached to the body of the crop item. And this is also true when the crop item is picked in a ripe state ready for immediate consumption because the stem denies access to the pulp of the fruit by oxygen, bacteria, insects and the like.
Several harvesting tools and manipulators have been suggested in the prior art. These include the mechanical hand and intake head described in U.S. Pat. No. 4,975,016 to Pellens et al, the robot hand described in U.S. Pat. No. 4,663,925 to Terada, the fruit picking device described in U.S. Pat. No. 5,005,347 to Kedem et al., the harvesting hand described in U.S. Pat. No. 4,718,223 to Suzuki et al., the robotic fruit harvester described in U.S. Pat. No. 4,532,757 to Tutle, the fruit harvesting apparatus described in U.S. Pat. No. 4,519,193 to Yoshida et al., and others.
These conventional harvesting tools and manipulators suffer from a number of disadvantages. First, the time taken to reach the crop items from an initial position is relatively long, thereby lowering the crop harvesting rate. Second, some of the tools and manipulators have difficulty in harvesting crop items which are not hanging from substantially vertical stems, thereby leaving some of the crop items still on the growth sources either to be picked manually at a later stage or disregarded thereby lowering the actual yield of crop items from the potential yield of crop items from given growth sources. And lastly, many of the conventional harvesting tools and manipulators cause considerable damage to the growth sources by pulling on the growth sources during the harvesting of the crop items.
Therefore, there is a need for novel automatically guided tractors, trolleys, and the like, for pursuing a pre-determined path through growth sources of crop items and for novel harvesting tools and manipulators for harvesting crop items hanging by stems from their growth sources which overcome the disadvantages of conventional apparatus.